What do the "options" mean for preamp tubes?

[rnolan]

Copied From Doug's Tubes (excellent site BTW (http://www.dougstubes.com/faq#g1)) This is from Doug's FAQs well worth a read if you want to understand your tubes better.
"Dual triode preamp tubes like the 12AX7 really have two separate tubes inside one glass envelope. When the plate current draw of each triode is the same(as evaluated by our VTV testers), we refer to that as having balanced triodes. These may or may not also have the same gain on each triode but are still considered balanced. Chances are that these are not required for your particular circuit. What we have observed after testing 1000's of preamp tubes using the Vacuum Tube Valley dual triode characterizer is that tubes with balanced triodes seem to be more consistent with a standard specification tube as to gain and low noise and microphonics."

"Balanced: When the plate current draw of each triode is the same, we refer to that as having balanced triodes.

High Gain:  Tubes that measured to have higher gain.

Matched:  Each triode of the preamp tube has matching gain."